First of all, dogs don't sweat. He must have been drooling or salivating excessively, which is pretty common with anxiety.

Quote:

We both took the Wed. off work so we could slowly get him used to being alone

One day is not enough to slowly get him used to anything at ALL, and it was too soon to leave him alone for an hour. It's difficult to say if he truly has sep. anxiety, or just flipped out at all that has happened to him in a short time:

He has been abandoned
Lived in the shelter (VERY stressful)
Been neutered
Gone to a new home with new people
Spent his first day watching you come and go constantly
and worst of all-
Been left all day in a shipping crate the very next day.

No wonder he is freaking out. You say that when he broke out of his crate, he did no damage in the house? Could you try leaving him out, maybe gated in the kitchen?

Shipping crates are not intended for leaving dogs in for extended periods of time, and as I said, ONE day is certainly not enough to train a 2 yr old dog to go into any crate all day if he's not used to it. Personally, I would never leave any dog in any crate for a normal working day (I'm assuming at least 8 hours?) of 8 hours or more - but that's just me.

If you must use a crate, get the biggest one you can find - Great Dane size - and make sure it's open wire and not enclosed.

IF possible, could you take a vacation now, to really try and get him used to your absences in short intervals and slowly? This is what people often do when getting new dogs and puppies - to ease the dog into spending more time alone.

My dog was 2 1/2 when I adopted her, and I know if I had left her in a crate all day the very next day after bringing her home, she probably would have freaked out too, and she does not have any sep. anxiety at all.